Cryptology ePrint Archive: Report 2006/234

RFID Security: Tradeoffs between Security and Efficiency

Ivan Damg{\aa}rd and Michael {\O}stergaard

Abstract: Recently, Juels and Weis defined strong privacy for RFID tags. We add to this definition a completeness and a soundness requirement, i.e., a reader should accept valid tags and only such tags. For the case where tags hold independent keys, we prove a conjecture by Juels and Weis, namely in a strongly private and sound RFID system using only symmetric cryptography, a reader must access virtually all keys in the system when reading a tag. It was already known from work by Molnar et al. that when keys are dependent, the reader only needs to access a logarithmic number of keys, but at a cost in terms of privacy: for that system, strong privacy is lost if an adversary corrupts only a single tag. We propose protocols offering a new range of tradeoffs between security and efficiency. For instance the number of keys accessed by a reader to read a tag can be significantly smaller than the number of tags while retaining security, as long as we assume suitable limitations on the adversary.

Category / Keywords: cryptographic protocols, RFID security, symmetric cryptography, protocols

Date: received 7 Jul 2006, last revised 31 Jul 2006

Contact author: ivan at daimi au dk

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Version: 20060731:064427 (All versions of this report)

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